Narrowband random access channel occasions
Certain aspects of the present disclosure provide techniques for narrowband random access channel (RACH) occasions. A method that may be performed by a user equipment (UE) includes receiving, from a network entity, a configuration indicating one or more frequency resources for a RACH procedure, wherein the one or more frequency resources are arranged within a set of frequency resources allocated for RACH transmissions. The method further includes performing the RACH procedure based at least in part on the configuration.
1. An apparatus for wireless communication by a user equipment (UE), comprising:
one or more processors individually or collectively configured to execute instructions stored on one or more memories and to cause the UE to:
receive, from a network entity, a narrowband random access channel (RACH) configuration indicating one or more narrowband frequency resources, for a RACH procedure, that are arranged within a set of frequency resources allocated for RACH transmissions for non-narrowband UEs, wherein:
the one or more narrowband frequency resources have a bandwidth that is in compliance with a capability of the user equipment;
the capability supports a first carrier bandwidth for a first frequency range and a second carrier bandwidth for a second frequency range;
the narrowband RACH configuration includes:
a number of the one or more narrowband frequency resources; and
an offset between a starting point of the one or more narrowband frequency resources and a lowest frequency of the set of frequency resources allocated for RACH transmissions for the non-narrowband UEs; and
perform the RACH procedure based at least in part on the narrowband RACH configuration.
2. The apparatus of claim 1 , wherein:
the capability includes a narrowband capability; and
the narrowband capability supports the first carrier bandwidth of 20 MHz for the first frequency range and the second carrier bandwidth of 100 MHz for the second frequency range.
3. The apparatus of claim 1 , wherein the offset is indicated in terms of transmission occasions or physical resource blocks.
4. The apparatus of claim 1 , wherein the one or more processors are further configured to cause the UE to receive the narrowband RACH configuration in system information.
5. The apparatus of claim 1 , wherein the one or more processors are further configured to cause the UE to:
identify that the one or more narrowband frequency resources are at least partially outside a bandwidth part assigned to the user equipment;
select other one or more narrowband frequency resources within the bandwidth part for the RACH procedure in response to the identification; and
transmit a preamble to the network entity via the other one or more narrowband frequency resources.
6. The apparatus of claim 5 , wherein the one or more processors are further configured to cause the UE to:
receive, from the network entity, an indication of a retuning offset; and
select the other one or more narrowband frequency resources based on the retuning offset.
7. The apparatus of claim 5 , wherein the one or more processors are further configured to cause the UE to select the other one or more narrowband frequency resources based on the one or more narrowband frequency resources.
8. The apparatus of claim 5 , wherein the one or more processors are further configured to cause the UE to transmit the preamble after waiting a gap in time from receiving the narrowband RACH configuration to tune to the other one or more narrowband frequency resources.
9. The apparatus of claim 5 , wherein the one or more processors are further configured to cause the UE to:
receive, from the network entity, an indication to use a same subband as the other one or more narrowband frequency resources for reception of a RACH response from the network entity; and
receive, from the network entity, a RACH response via the other one or more narrowband frequency resources based on the indication.
10. The apparatus of claim 5 , wherein the one or more processors are further configured to cause the UE to:
receive, from the network entity, an indication to use the one or more narrowband frequency resources for reception of a RACH response from the network entity; and
receive, from the network entity, a RACH response via the other one or more narrowband frequency resources based on the indication.
11. The apparatus of claim 10 , wherein the one or more processors are further configured to cause the UE to receive the RACH response after waiting a gap in time from transmitting the preamble to tune to the one or more narrowband frequency resources.
12. An apparatus for wireless communication by a network entity, comprising:
one or more processors individually or collectively configured to execute instructions stored on one or more memories and to cause the network entity to:
transmit, to a user equipment (UE), a narrowband random access channel (RACH) configuration indicating one or more narrowband frequency resources, for a RACH procedure, that are arranged within a set of frequency resources allocated for RACH transmissions, wherein:
the one or more narrowband frequency resources have a bandwidth that is in compliance with a capability of the user equipment;
the capability supports a first carrier bandwidth for a first frequency range and a second carrier bandwidth for a second frequency range;
the narrowband RACH configuration includes:
a number of the one or more narrowband frequency resources; and
an offset between a starting point of the one or more narrowband frequency resources and a lowest frequency of the set of frequency resources allocated for RACH transmissions for non-narrowband UEs; and
perform the RACH procedure based at least in part on the narrowband RACH configuration.
13. The apparatus of claim 12 , wherein:
the capability of the UE includes a narrowband capability; and
the narrowband capability supports the first carrier bandwidth of 20 MHz for the first frequency range and the second carrier bandwidth of 100 MHz for the second frequency range.
14. The apparatus of claim 12 , wherein the offset is indicated in terms of transmission occasions or physical resource blocks.
15. The apparatus of claim 12 , wherein the one or more processors are further configured to cause the network entity to transmit the narrowband RACH configuration in system information.
16. The apparatus of claim 12 , wherein the one or more processors are further configured to cause the network entity to:
identify that the one or more narrowband frequency resources are at least partially outside a bandwidth part assigned to the UE;
select other one or more narrowband frequency resources within the bandwidth part for the RACH procedure in response to the identification; and
receive a preamble from the UE via the other one or more narrowband frequency resources.
17. The apparatus of claim 16 , wherein the one or more processors are further configured to cause the network entity to:
transmit, to the UE, an indication of a retuning offset; and
select the other one or more narrowband frequency resources based on the retuning offset.
18. The apparatus of claim 16 , wherein the one or more processors are further configured to cause the network entity to select the other one or more narrowband frequency resources based on the one or more narrowband frequency resources.
19. The apparatus of claim 16 , wherein the one or more processors are further configured to cause the network entity to receive the preamble after waiting a gap in time from transmitting the narrowband RACH configuration to tune to the other one or more narrowband frequency resources.
20. The apparatus of claim 16 , wherein the one or more processors are further configured to cause the network entity to:
transmit, to the UE, an indication to use a same subband as the other one or more narrowband frequency resources for reception of a RACH response from the network entity; and
transmit, to the UE, a RACH response via the other one or more narrowband frequency resources based on the indication.
21. The apparatus of claim 16 , wherein the one or more processors are further configured to cause the network entity to:
transmit, to the UE, an indication to use the one or more narrowband frequency resources for reception of a RACH response from the network entity; and
transmit, to the UE, a RACH response via the other one or more narrowband frequency resources based on the indication.
22. The apparatus of claim 21 , wherein the one or more processors are further configured to cause the network entity to transmit the RACH response after waiting a gap in time from receiving the preamble to tune to the one or more narrowband frequency resources.
23. A method of wireless communication by a user equipment, comprising:
receiving, from a network entity, a narrowband random access channel (RACH) configuration indicating one or more narrowband frequency resources, for a RACH procedure, that are arranged within a set of frequency resources allocated for RACH transmissions for non-narrowband UEs, wherein:
the one or more narrowband frequency resources have a bandwidth that is in compliance with a capability of the user equipment;
the capability supports a first carrier bandwidth for a first frequency range and a second carrier bandwidth for a second frequency range;
the narrowband RACH configuration includes:
a number of the one or more narrowband frequency resources; and
an offset between a starting point of the one or more narrowband frequency resources and a lowest frequency of the set of frequency resources allocated for RACH transmissions for the non-narrowband UEs; and
performing the RACH procedure based at least in part on the narrowband RACH configuration.
24. A method of wireless communication by a network entity, comprising:
transmitting, to a user equipment (UE), a narrowband random access channel (RACH) configuration indicating one or more narrowband frequency resources, for a RACH procedure, that are arranged within a set of frequency resources allocated for RACH transmissions, wherein:
the one or more narrowband frequency resources have a bandwidth that is in compliance with a capability of the user equipment;
the capability supports a first carrier bandwidth for a first frequency range and a second carrier bandwidth for a second frequency range;
the narrowband RACH configuration includes:
a number of the one or more narrowband frequency resources; and
an offset between a starting point of the one or more narrowband frequency resources and a lowest frequency of the set of frequency resources allocated for RACH transmissions for non-narrowband UEs; and
performing the RACH procedure based at least in part on the narrowband RACH configuration.